Earlier quoted context omitted.
Yeah, in a new york minute. This is already built into iOS in their newer Find My Phone. The carriers also know who and where we are just need to add in covid testing data. The problem is that even if it is decentralized and OSS, then the average user can't/won't install it. If it is simple and easy (centralized), then it becomes a honey pot for the government.
Can you please explain or give a link, how can I use Find My Phone for anything coronavirus-related?
You can't, but apparently Find My Phone uses Bluetooth to find nearby phones and thats the same technology that Bluetooth contact tracing for coronavirus would use.